The present invention relates to an automatic electronic sewing machine and, more particularly, to a digitalized buttonhole switch control in an automatic electronic sewing machine.
An automatic electronic sewing machine including a read only memory (ROM) and a random access memory (RAM) is proposed in copending application, AUTOMATIC ELECTRONIC SEWING MACHINE, Ser. No. 843,639, filed Oct. 19, 1977 by Tousaku Nakanishi, Kazuo Suzuki, Masayasu Makino, Nobuyoshi Miyao and Hirokazu Koda and assigned to the same assignee as the present application.
In the conventional automatic electronic sewing machine such as disclosed in the above-mentioned U.S. patent application Ser. No. 843,639, buttonhole stitch formation is controlled through the use of a guide plate which determines the button size. Therefore, buttonhole stitch formation is difficult to perform in the conventional automatic electronic sewing machine.
Accordingly, an object of the present invention is to provide a digital control system for performing buttonhole stitch formation in an automatic electronic sewing machine. Another object of the present invention is to facilitate buttonhole stitch formation in an automatic electronic sewing machine.
Other objects and further scope of appicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a read only memory (ROM) stores digital data for conducting buttonhole operation. More specifically, the read only memory (ROM) includes two subsections one for storing digital data related to the stitch pattern in the forward direction of the buttonhole, and the other for storing digital data related to the stitch pattern in the backward direction of the buttonhole.
A first control instruction derived from a keyboard unit functions to conduct the buttonhole stitch formation in the forward direction in accordance with the digital data stored in the read only memory (ROM). The length of the stitch formation in the forward direction is manually selected by the operator. A storage means is provided for storing the information related to the length of the buttonhole stitch formation in the forward direction, or the repetition number of a unit zigzag pattern in the forward direction.
A second control instruction derived from the keyboard unit functions to conduct the buttonhole stitch formation in the backward direction in accordance with the digital data stored in the read only memory (ROM). The length of the stitch formation in the backward direction is automatically limited to the length corresponding to the information stored in the storage means.
In a preferred form, indication means are provided for indicating whether the buttonhole operation is now conducted in the forward direction or in the backward direction.